1. Field of the Invention
The invention relates in general to a plasma display, and more particularly, to a brightness correction apparatus and method of a plasma display.
2. Description of Related Art
Generally, display apparatus can be classified into two major types. One is the display using the cathode ray tube (CRT), and the other is the flat panel display. Being lighter and thinner than the cathode ray tube display, and having a display image that is neither distorted nor interfered by a magnetic field, the flat panel display has gradually replaced the conventional cathode ray tube display to become the user favorite.
Commonly seen flat panel displays in the market include the liquid crystal display (LCD) and plasma display panel (PDP). The plasma display panel, which can be fabricated with a large display area, is specifically applicable for certain events and locations. In the discharge driving circuit of the plasma display, a field is typically divided into several sub-fields, while each sub-field has a specific number of sustain pulses. The display for different gray scale inputs is then achieved by a different allocation combination for each sub-field.
Referring to FIG. 1, a field of a plasma display is divided into several sub-fields. FIG. 1 shows an example of dividing a field into 8 sub-fields SF0 to SF7, and each them includes a constant address period 10 and a different sustain period 20 according to various numbers of sustain pulses. The more the sustain pulses are, the longer the sustain period 20 lasts. Assuming that 8 bits are used to represent the gray scale of the plasma display, there are 256 gray scales, 0–255, to be represented. Assuming that the number of the sustain pulses of the sub-field SF0 is 5, and the number of the sustain pulses SF1 to SF7 are 10, 20, 40, 80, 160, 320 and 640, respectively, the sub-fields SF1 to SF8 represents the gray scales 2, 4, 7, 13, 26, 46, 68 and 90, respectively. Other gray scales can be assembled by allocations of different sub-fields. For example, the gray scale 5 can be obtained by the combination of the sub-fields SF0 and SF2, and the gray scale 160 can be represented by the combination of the sub-fields SF5 and SF7. Accordingly, different gray scale data corresponding to the sustain pulse numbers further correspond to the display brightness of the display pixels.
However, due to factors such as discharging features or luminescence properties of fluorescent objects, a linear relationship between the actual display brightness and the sustain pulse number cannot exist. Normally, as shown in FIG. 2, the larger the sustain pulse number, the large the deviation is. Therefore, a brightness error between the ideal display brightness and the actual display brightness of the gray scale data occurs. To correct such brightness errors, U.S. Pat. No. 5,943,032 issued to Fujitsu Corp. proposed a method to adjust the sustain pulse number, and U.S. Pat. No. 6,088,009 issued to LG Corp. disclosed a method for adding a pseudo pulse to obtain a simple linear relationship between the gray scale and the brightness. However, as the adjustment is applied to the sustain pulse number for each sub-field only instead of adjusting each gray scale, the effect is still limited.